The suspect is accused of stabbing five classmates in a locker room Tuesday

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Families reunited use their cell phones outside Mountain View High School where several students were stabbed Tuesday, Nov. 15, 2016, in Orem, Utah. Police say a 16-year-old has been booked on attempted murder for the stabbings.

A Utah teenager accused of stabbing five classmates in a high school locker room was booked Wednesday on suspicion of five counts of attempted murder, police said.

The 16-year-old suspect was being held in a juvenile detention center and has not yet been formally charged by county prosecutors, Orem Police Lt. Craig Martinez said. His name was being withheld because of his age.

Martinez said investigators believe they have discovered a motive for the attack at Mountain View High School in Orem, a city of about 90,000 people south of Salt Lake City.

But he declined to provide details because the suspect is under age 18 and because investigators "are not medical professionals."

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He declined to elaborate, but he added that investigators have concluded the teen's attack was not motivated by race, ethnicity or because he had been bullied. The victims just happened to be near the suspect in the locker room when he attacked, Martinez said.

Police and school officials have said the suspect is a straight-A student with no record of disciplinary action against him who was in his first year at the high school after being home-schooled.

Police determined the teen stabbed himself in the neck when a police officer assigned to the school arrived to the locker room where teachers had cornered the student, Martinez said.

The victims are all expected to survive. The two most seriously injured teens had their conditions upgraded from critical to serious condition Wednesday, Utah Valley Hospital spokeswoman Janet Frank said. The rest of the victims have been released, she said.

The attack spread fear and panic among students who described a panicked and gruesome scene immediately after the stabbings, with victims running from the locker room covered in blood and the school placed on lockdown. Police said the knife used in the attack had a 3-inch blade.

On Wednesday, authorities released chilling 911 recordings of callers inside the school pleading with police for help.

Orem police posted an apology letter online they said was from the unidentified parents of the suspect. The parents in the unsigned letter said that none of the victims had done anything to hurt their son and that the stabbings were not racially or ethnically motivated.

"We are at a loss to express how deeply sorry we are for the pain and injury caused," the letter said.

The suspect's parents were just as shocked as anyone by their son's actions, Martinez said.

"They're trying to figure out why this happened, just like the rest of us are," Martinez said about the parents. "They are obviously distraught about the situation."

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